We're going to turn to what is being called biblical flooding across colorado. Residents said they've never seen anything like it. Homes up to their roofs with water. Rescuers using canoes to get people to safety. As rivers rage with roads ripped out. There's no end to the many izry in sight. Ginger zee is right in the middle of it in boulder. Hey, ginger. I'm standing at the bank of boulder creek, as you can hear and see, it's been called boulder rapids. There's some good news. This bench, as of 24 hours ago, underwater. Now, just caked in mud. This is what happens when you get a foot or 13 inches of rain. Look at the numbers. Incredible rainfall totals. And the bad news is, after the nine-plus inches in places like colorado springs, there's more to come. This ordeal is not over. Stranded and submerged, the colorado land cape racing away, as those trapped by rising waters. Like the ocean out there. Reporter: Dozens of homes. Entire neighborhoods, up to the roof in murky run off. It surrounded the entire house. Reporter: Some caught riding it out. Others, plowing through the historic floods in pickup trucks. In weld county, farms isolated on islands. Never, ever has this water been this high. I've got three horses. I hope they're alive. We had to get out so quick. homes. Congested, toppled by the devastating waters. In estes park, this dramatic video of a woman desperately holding on, as rescue workers zip line her to safety. And from inside the fire truck, the floodwaters, bubbling over the windshield. I would consider this a 100-year flood. Reporter: Thousands evacuated from their homes. 4 dead and more than 180 now unaccounted for. President obama declaring a state of emergency friday. And it's not just colorado. Parts of new mexico are getting up to four inches of rain an hour at times. At least 25 homes evacuated. Countless roads impassable. The remorseless waters devouring highways. Homes crumbling in the force of full weekend forecast of more rain. We have brand-new information. I'll take you to a different river. The south platte. This river gauge has surged to 19-plus feet. The old historic record was around 11. You know how bad it still is this morning north of denver. Let's look, then, at what's to come. I wish I had better news. When you take the foot-plus of rain that's already fell, the raging rapids behind me and add another one to two inches that's coming in tonight. The front backing in, the monsoonal moisture budding up against it. This is not a good situation. The danger is still in place here. People have to be on alert. We'll be coming back with our nation's weather. And the tropics firing up. Another area in texas going to get a lot of rain this weekend. More to come in colorado. It is not over. Still a dangerous situation. We'll be coming back to you. We're hearing extraordinary stories of survival and rescue this morning about colorado. We're hearing from a man who got trapped after his car was flipped over by a wall of water. His rescue, as you can see right here, caught on camera. And abc's clayton sandell in the flood zone this morning. Reporter: Unimaginable loss. It's all gone. Reporter: Thousands of colorado residents forced from their homes. The national guard airlifting 300 out of the stranded community of jamestown. Reuniting them with loved ones. Still shaken by all they've seen. No one would ever imagine all this. The devastation over there is immense. It's like everything you know and love. And you see it get swept away in a matter of hours. One friend dead. And no idea, you know, when we can go back and what will be left when we get back. Reporter: We were there the moment troops brought residents from another devastated town to safety. The neighbors' house fell off into a little creek, now a raging river. Just got swept away. Gone. There's no other word but catastrophic. I've never, ever seen anything like this. Reporter: The word on many minds, survival. Something roy ortiz knows too well. This is the underside of ortiz's grand prix. Flung into the rapids thursday, on his way to work. Flash floods tearing away the road beneath him. For two hours, the father of four was trapped and quickly sinking. Pray, I want to survive. Reporter: One of the first to arrive, firefighter john cook. We pounded on the bottom of the car. I rescue people looked at me. And I raised my hand. I'm alive. Reporter: Ortiz was caught in a driver's worst nightmare. One where the road suddenly becomes a river. As cook and his team tried to save him. Ortiz tried to calm himself by thinking about his family. Only a small pocket of air helping to keep him alive. My family. Reporter: For "good morning america," clayton sandell, abc news, boulder, colorado. He's one of the lucky ones. Nearly 200 are still unaccounted for. Our thanks to clayton for that.

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